Recording apparatus



Feb. 21, 1939. H F R w 2,147,668

RECORDING APPARATUS Filed April 30. 1935 26 27 10 ll Z2 Z0 5 l6 1 I7 I l5 l9 INVENTOR.

HERMAN F. PFEIFFER gb/u W ATTORNEYJ Patented Feb. 21 1939 UNITED STATES PATENT oFFicE RECORDING APPARATUS corporation of Maine Application April 30, 1935, Serial No. 19,076

2 Claims.

The present invention relates to recording apparatus, particularly adapted for recording the length of short time intervals, which may be defined by successive electric impulses and may reour at frequent intervals as in echo distance measuring systems. Such a recording device is also useful in any system where time intervals of the order of 0.01 second and perhaps recurring as often as three or four per second must be recorded with an accuracy of one half of one percent.

In echo distance measuring systems, as is well known, a wave energy impulse is transmitted and the reflection from the object whose distance is being measured is received. The time interval 5 between the instant of production of the signal andthe receipt of the echo is a measure of the distance. In order to obtain a substantially continuous indication of varying distance as, for example, of the depth of water beneath a ship or the height of an aircraft above the ground, it is customary to emit the signal impulses periodically. It will be evident that in order to obtain a record of a. varying distance, such as the depth of water beneath a ship, it is necessary to record a long series of rapidly recurring individual timeinterval measurements. It also should be noted that the time intervals to be measured are extremely short, viz. of the order of 0.01 second, and that a measurement is usually made every two to four seconds or even more often.

A recorder for automatically making a record of such a series of measurements is described in the copending application of Edwin E. Turner, Jr., Serial No. 561,213, filed September 4, 193,1,

maturing into Patent No. 2,108,089, granted February 15, 1938. This recorder comprises an arm rotated at a constant speed and arranged to sweep over the record paper once in each revolution. At the end of the arm an electromagnet and armature carrying a stylus are mounted. When the stylus passes a zero line on the record paper, the signal is emitted and when the echo returns, the stylus is caused to mark the paper. The record paper is coated with wax which is 5 removed by the stylus when a mark is being made.

record paper by the stylus tended to fill the space between the electromagnet poles and the armature, thereby preventing proper operation. Pur thermore, the cleaning of the device was difficult due to the construction employed. In addition 1 the cylindrical or conical stylus which was used 5 would often tear the paper.

The present invention provides an improved recorder of the type described, and particularly an improved electro-magnet and stylus unit for such a recorder. 10

The present invention will best be understood by reference to the accompanying drawing in which Fig. 1 shows the general arrangement of the stylus carrying arm with respect to the record paper; Fig. 2 shows an improved electromagnet 15 and stylus unit; Figs. 3 and 4 show details of the arangement shown in Fig. 2; Fig. 5 shows a modification of the detail shown in Fig. 4; Fig. 6 shows a modification of the device shown in Fig.

2; Fig. 7 is a detail of the arrangement shown in 20 Fig. 6; and Fig. 8 shows a perspective view of the electromagnet core.

As shown in Fig. 1, an arm 1 mounted on the shaft 2 is rotated at a constant speed in the direction of the arrow 5. At the end of the arm I an electromagnet and marking stylus unit 3 is mounted which in each revolution of the arm sweeps across a record paper shown at 4. The paper 4 is moved in the direction of the arrow 6 by a mechanism, which is notshown, but which en- 30 gages holes 1 in the edges of the paper.

The paper chart is suitably graduated in units of distance by the parallel lines 8. The first line at the left side of the chart is the zero line. At the instant the stylus passes over this line, the 35 wave energy signal is emitted. When the echo or reflection from the object whose distance is being measured is received, the stylus is impelled against the record paper which is coated with wax. The stylus scrapes off a portion of this wax covered by a metal cover ll U-shaped in cross 5 I section having projections I! with holes therein forming bearings for the armature axis. Instead of being U-shaped in cross section the cover ll may simply be composed of two plates fixed one to each side of the core. 6B

' the stylus reduces the amount of wax removed sion terminating in an eye i6 which may conveniently be fastened to the magnet core by means of the screw H. I A flat spring I8 is riveted to the.

armature by the rivets l9 and serves to tension the armature away from the electromagnet. The tension provided by the spring may be adjusted by meansof the adjusting screw 20. It will be evident that with the construction which has just been described, the armature is readily removable from the electromagnet for it is simply necessary to remove the screw l7 and to pull out the pin i5. If the end of the spring i8 which fits over the screw 20 is made in the form of a slot, the, whole armature may then easily be removed.-

A modification of this construction is shown in,

detail in Fig. 5. According to this modification the pin shown at 2! is not provided with anex tension and an eye l6, but is ,firmly fixed in the armature.

screws H and 22 whereupon the armature can also be removed.

At the opposite end'of the armature the mark- 'ing stylus 23 is fixed. The stylus 23 is substantially oval in cross section. .It has a straight portion 23 and a bent portion 25. An end view of the armature and stylus is shown at the left in Fig, 2.

The left .pole of the electromagnet is covered by a cover plate 26 shown in detail in Fig. 3. The cover plate 26 is fastened to the core by means of screws 27. The'upper portion 'of the plate is U-shaped in cross section. The portion of the plate projecting below the electromagnet pole has.

the side of the plate cut away and terminates in a right-angled extension 28, as shown in Fig.3. A pin -29 serves as a stop for the armature. The

stylus 23 passes freely through a hole 30 in the extension 28.v The shape of the cross sectionof.

from the record paper when .a mark is being made and-makesa narrower sharper line as compared with a stylus of circular cross section as heretofore used. Furthermore, the bend at the lower end'25 of the stylus is such that the stylus makes an angle of approximately 55 degrees. with the plane'of the paper instead of 90 degrees as heretofore used. Thisperrhits it to ride over the edge of the record paper without tearing the paper in the event that the stylus should at that instant be in contactwith the paper. I v a One side of the cover plate ii is" in this case made removable by removing the The extension 28 of. the cover plate 26 and the oval instead of circular cross section of the stylus reduces to a minimum the amount of wax which can collect along the surface ofthe stylus so that none of the wax can get in between the armature and the pole face.

- A modification of the armature mounting arrangement shown in Figs. 2, 4 and is illustrated in, Figs. 6 and 7. The armature I3 is in this case terminated at the thickened portion M .with an upwardly extending portion. 3! at right angles to the flat portion l3. The tensio ning spring, as shown at 32, is free at the lower end and bears against the upwardly projecting end 3! of the armature. The opposite end of the spring 32 extends beyond the adjusting screw 33 and is bent to bear against the end of the magnet core. The thickened portion M of the armature is provided with a pin 3% which is similar to the pin 2| in Fig. 5. This pin similarly fits in-to suitable holes in the cover plate 35. This construction is somewhat easier to manufacture inasmuch as it is not necessary to rivet the spring to the armature.

Having now described my invention, I claim: -1. In a recording instrument, a recordingelement including a U-shaped magnet, a flat armature extending across the polesof the. magnet and carrying a marking stylus, means for supporting the armature comprising a pair of cars extending downwards and outwards from opposite faces of one of the poles of said magnet, one on each side of said armature, said armature and said ears having coaxial apertures therein, a pivot pin .adapted to 'pass through said apertures, said pivot -one of the poles of said magnet, one on each side of said armature, said armature and said ears having coaxial apertures therein, a pivot pin adapted to pass through said apertures, said armature having an extension beyond said aperture, a'right-angled leaf spring secured by one arm to said armature extension in a position so that the other arm extends substantially parallel to said magnet pole and having an aperture therein and a single screw adapted to pass through said aperture and into said pole for tensionin'g said armature.

HERMAN F. PFEIFFER. 

